Tire-carrying wheels for motor vehicles and the like are attached to an axle hub or brake drum of the vehicle body by passing heavy threaded bolts called lugs through holes in the wheel and tightening the wheel thereto using wheel or lug nuts. Proper wheel nut torque for attachment of automobile wheels is typically 95-100 ft.-lbs. (129-140 Nm). Using conventional L-shaped lug nut wrenches, considerable strength is required to achieve such torque. Even with the long handle, the length of the achievable force application moment is limited. Moreover, there is a propensity for the nut receiving box end of the wrench to unseat during manipulation of the arm, which may undesirably damage chrome capped and similar wheel nuts.
One problem with the interposition of any gearing mechanism to mechanically provide the same effect as a larger moment without extending the wrench handle length, is the need to fix rotation of the mechanism relative to rotation of the nuts. To accomplish this by means requiring contact with the ground maintains some of the disadvantages inherent in the long arm of the current wrench.
It is an object of the present invention to provide compact wheel-braced, torque multiplying apparatus for facilitating the loosening or tightening of the lug nuts of a motor vehicle wheel or the like.
In accordance with one aspect of the invention, a compact mechanical assembly is provided having input means for receiving a torque applied by a lever arm, gear means for multiplying the applied torque, and output means for applying the thus multiplied torque to a lug nut of a wheel. Means are further provided to brace a stator portion of the gear means to fix the same relative to the wheel or lug.
In an illustrative embodiment of the invention, described in greater detail below, the gear means comprises an eccentrically driven orbiting gear set, wherein a first cylindrical gear element serving as the input means functions as an epicycling coupling between a tubular housing and a second cylindrical gear element which is axially-spaced from the first element and concentrically located within the housing to serve as the output means. A bracing member located nonrotationally annularly of the housing is configured to fix the housing against rotation between the outside of the axle hole rim and the inside rim of the wheel.
In a modified embodiment, the assembly is braced internally by keying the second gear element to the lug to act as the stator, and configuring the housing to act as the output means for rotating the nut.